Disc drives are sensitive to moisture, chemical contamination, and particulate contamination. Chemical contaminants, such as hydrocarbons and acid gases, can condense onto a disc and degrade the head/disc interface and possibly corrode the heads. Particulate contaminants can lead to head and media scratches, and can cause read/write errors and can lead to interface failure and head crashes. As the drive heads become smaller and areal densities increase, disc drives are more susceptible to these contaminants.
Most current disc drives include a filter to remove particles (i.e., a particle filter) and a filter to remove gaseous contaminants (i.e., a chemical filter). The chemical filter typically includes activated carbon. It is well known that a life span of a chemical filter is limited by the amount of adsorption material (e.g., the activated carbon) and its surface area available for adsorption. With the continuing tendency to increase areal densities of disc drives and to reduce their size, having a relatively small chemical filter, with a relatively limited surface area for adsorption, may result in potential susceptibility to contaminants.
Breather and recirculation filters have been used in hard disc drives for removing contaminates. Typically, recirculation filters have been included to remove unwanted particulates. They are not, however, typically suitable for removing organic vapors since they do not have a capacity for permanently adsorbing organic vapors. To provide enhanced organic vapor removal, activated carbon or other adsorbent material has been used in recirculation filters as well as breather filters. For example, activated carbon in the form of granules or fiber can adsorb and remove organic vapors from the air within a disc drive housing.
The present disclosure provides a recirculation chemical filter for inside disc drive enclosures.